xvi MIMICRY IN TUJPAIA 511
perforated as in JZrinacews (it is not so in Gyvnnura and .B^/omys),
but on the whole it conies nearest to Hylornys.
Fam, 2. Tllpaildae.—This family contains the genera Tupaia,
and Ptilocercus. Tupaia is Oriental in range, extending as far
east as Borneo. There are a dozen or so of species, which are
generally arboreal and have the outward aspect of Squirrels. It
has been suggested that this is a case of mimicry,, the animal
gaining some advantage by its likeness to the JRodent. The
name Tupaia, it should be added, means Squirrel, arid the long-
nosed Squirrel, JSciurus laticandatus, is so extraordinarily like it
that " one has to look at the teeth" to distinguish them.
Moreover, this Squirrel, like some Tupaias, lives largely on the
ground among fallen logs. Titpaia resembles a Lemur in the
complete orbit. The dental formula is If C-J- Pin f- M § = 38.
The sublingua, too, is stated by Garrod to be like that of
Cliiromys. There is a minute caecum in T. "belangeri, none in
Ptilocerciis'1 has a pen-like posterior portion to the tail, a
modification "which is found in other groups of animals. The
tail of certain Phalangers, for instance, shows this same modi-
fication. The rest of the tail is scaly. The animal, as was
pointed out by Dr. Gray,2 looks very much like a Phalanger.
The orbit is entire as in Tupaia. The fingers and toes are five.
The one species, called after Sir Hugh L*ow, G.C.M.G-., JF*. lowi, is
a ^Borneaii animal.
Fam. 3. Oentetidae.—This family is entirely confined to the
Island of Madagascar. It includes some seven genera. The best-
known genus is Oentetes. O. ecaudatu$> the Tanrec, Tenrec, or
Tendrae, is an animal a foot or so in length, without a tail, and with
forty-four teeth.3 The immature animal is so different from the
parent as to appear quite a different form. It has three narrow
rows of spines along the back, which do not wholly disappear
until the permanent dentition has been acquired. Even then.
the hairs are of a rather spiny character, particularly those upon
the back of the head, which are erected when the animal is
1 "USTotes on the Visceral Anatomy of the Tupala of Burmah/' JP-roc. Zool, Soc*
1879, p. 301.
2 Proc. Zool. Soc. 1848, p. 23.
* I quote Woodward, JProc. Zool. Soc. 1896, for this dentition. The fourth
molar of the lower jaw is not always present. It conies late, and only old animals